Bacterial superantigens are the most potent T cell mitogens known. They stimulate large numbers of T cells by directly binding to the side of the MHC class II and T cell Receptor (TcR) molecules. Because they override the normally exquisite MHC restriction phenomenon of T cell antigen recognition, they are prime candidates for either causing the onset of autoimmune diseases or exacerbating an existing autoimmune disorder.
The applicants have identified genes coding for four novel superantigens from S. pyogenes. It is broadly to these superantigens and polynucleotides encoding them that the present invention is directed.